Slow release cortisol implants result in impaired innate immune responses and higher infection prevalence following experimental challenge with infectious pancreatic necrosis virus in Atlantic salmon (Salmo salar) parr

Gadan, Koestan; Marjara, Inderjit S.; Sundh, Henrik; Sundell, Kristina; Evensen, Øystein

doi:10.1016/j.fsi.2012.01.004

Cited by 44 publications

(27 citation statements)

References 42 publications

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“…The higher mRNA expression of IFN type I, found in the +IPNV-F group compared to both –IPNV and +IPNV+F fish, in the proximal intestine and the head kidney is indicative of the early innate anti-viral response [43]. The simulated chronic stress in terms of elevated plasma cortisol levels, suppresses the response both systemically and locally in the intestine.…”

Section: Discussionmentioning

confidence: 94%

“…TaqMan qPCR was performed using commercial qPCR Master Mix No ROX Kit (Eurogentec, Liège, Belgium) in 20 µL reactions. The relative expression was calculated using the cycle threshold (Ct) number and the slope of the efficiency curve (E) of the reference gene and the target gene in the calculation:Primers for RNA expression of VP1, the RNA polymerase of IPNV, were previously published in Gadan et al 2012 [43] and used in 1000 nM concentrations for SYBRGreen detection of amplification after verification on the iQ5 platform, using the iQ SYBRGreen Supermix commercial kit in 20 µL reactions (Bio-Rad, Sundbyberg, Sweden). ELF1α was used as reference gene and melting curve analysis was used to verify specific products.…”

Section: Methodsmentioning

confidence: 99%

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Effects of Cortisol on the Intestinal Mucosal Immune Response during Cohabitant Challenge with IPNV in Atlantic Salmon (Salmo salar)

et al. 2014

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Infectious pancreatic necrosis virus (IPNV) causes high incidence of disease in salmonids during the first period after SW transfer. During this period as well as during periods of stress, cortisol levels increase and indications of a relationship between IPNV susceptibility and cortisol have been suggested. The intestine is an entry route and a target tissue for IPNV displaying severe enteritis and sloughing of the mucosa in infected fish. The mechanisms behind effects of the virus on the intestinal tissue and the impact of cortisol on the effect remain unclear. In the present study, Atlantic salmon post smolts treated with or without slow release cortisol implants were subjected to a cohabitant IPNV challenge. Analysis of genes and proteins related to the innate and acquired immune responses against virus was performed 6 days post-challenge using qPCR and immunohistochemistry. An increased mRNA expression of anti-viral cytokine interferon type I was observed in the proximal intestine and head kidney as a response to the viral challenge and this effect was suppressed by cortisol. No effect was seen in the distal intestine. T-cell marker CD3 as well as MHC-I in both intestinal regions and in the head kidney was down regulated at the mRNA level. Number of CD8α lymphocytes decreased in the proximal intestine in response to cortisol. On the other hand, mRNA expression of Mx and IL-1β increased in the proximal intestine and head kidney in IPNV challenged fish in the presence of cortisol suggesting that the immune activation shifts in timing and response pathway during simulated stress. The present study clearly demonstrates that IPNV infection results in a differentiated epithelial immune response in the different intestinal regions of the Atlantic salmon. It also reveals that the epithelial immune response differs from the systemic, but that both are modulated by the stress hormone cortisol.

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Section: Discussionmentioning

confidence: 94%

Section: Methodsmentioning

confidence: 99%

Effects of Cortisol on the Intestinal Mucosal Immune Response during Cohabitant Challenge with IPNV in Atlantic Salmon (Salmo salar)

et al. 2014

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“…Therefore, it is likely that during stressful events, the elevated circulating cortisol levels can modulate the expression of genes related to the complement pathway, such as C3. Such an effect can explain a higher susceptibility to pathogens in stressed fish, as the activity of the complement system would be suppressed [41]. …”

Section: Resultsmentioning

confidence: 99%

Effects of Cortisol Administered through Slow-Release Implants on Innate Immune Responses in Rainbow Trout (Oncorhynchus mykiss)

Cortés

Teles

Tridico

et al. 2013

International Journal of Genomics

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Cortisol is a key hormone in the fish stress response with a well-known ability to regulate several physiological functions, including energy metabolism and the immune system. However, data concerning cortisol effects on fish innate immune system using a more controlled increase in cortisol levels isolated from any other stress related signaling is scarce. The present study describes the effect of doses of cortisol corresponding to acute and chronic levels on the complement and lysozyme activity in plasma of the rainbow trout (Oncorhynchus mykiss). We also evaluated the effects of these cortisol levels (from intraperitoneally implanted hydrocortisone) on the mRNA levels quantified by RT-qPCR of selected key immune-related genes in the liver, head kidney, and spleen. For that purpose, 60 specimens of rainbow trout were divided in to two groups: a control group injected with a coconut oil implant and another group injected with the same implant and cortisol (50 μg cortisol/g body weight). Our results demonstrate the role of cortisol as a modulator of the innate immune response without the direct contribution of other stress axes. Our results also show a relationship between the complement and lysozyme activity in plasma and mRNA levels in liver, supporting the important role of this organ in producing these immune system proteins after a rise of cortisol in the fish plasma.

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“…Similar stressful farming conditions, including bad weather, handling, infection with sea lice, treatments for sea lice and other environmental stressors have in several studies been associated with decreased resistance to viral pathogens and increased disease susceptibility, including ISA [54,[56][57][58][59][60].…”

Section: Discussionmentioning

confidence: 99%

First field evidence of the evolution from a non-virulent HPR0 to a virulent HPR-deleted infectious salmon anaemia virus

Christiansen

McBeath

Aamelfot

et al. 2017

Journal of General Virology

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The putatively non-virulent subtype of infectious salmon anaemia virus (ISAV), ISAV-HPR0, is proposed to act as a progenitor and reservoir for all virulent ISAVs and thus represent a potential risk factor for the emergence of infectious salmon anaemia (ISA) disease. Here, we provide the first evidence of genetic and functional evolution from an ISAV-HPR0 variant (FO/07/12) to a low-virulent ISAV virus (FO/121/14) in a Faroese Atlantic salmon marine farm. The FO/121/14 virus infection was not associated with specific clinical signs of ISA and was confined to a single net-pen, while various ISAV-HPR0 subtypes were found circulating in most epidemiologically linked marine and freshwater farms. Sequence analysis of all eight segments revealed that the FO/121/14 virus was identical, apart from a substitution in the fusion (F) gene (Q 266 L) and a deletion in the haemagglutinin-esterase (HE) gene, to the FO/07/12 variant from a freshwater farm, which supplied smolts exclusively to the FO/121/14-positive net-pen. An immersion challenge with the FO/121/14 virus induced a systemic infection in Atlantic salmon associated with a low mortality and mild clinical signs confirming its low pathogenicity. Our results demonstrate that mutations in the F protein and deletions in the highly polymorphic region (HPR) of the HE protein represent a minimum requirement for ISAV to gain virulence and to switch cell tropism from a localized epithelial infection to a systemic endotheliotropic infection. This documents that ISAV-HPR0 represents a reservoir and risk factor for the emergence of ISA disease.

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Slow release cortisol implants result in impaired innate immune responses and higher infection prevalence following experimental challenge with infectious pancreatic necrosis virus in Atlantic salmon (Salmo salar) parr

Cited by 44 publications

References 42 publications

Effects of Cortisol on the Intestinal Mucosal Immune Response during Cohabitant Challenge with IPNV in Atlantic Salmon (Salmo salar)

Effects of Cortisol on the Intestinal Mucosal Immune Response during Cohabitant Challenge with IPNV in Atlantic Salmon (Salmo salar)

Effects of Cortisol Administered through Slow-Release Implants on Innate Immune Responses in Rainbow Trout (Oncorhynchus mykiss)

First field evidence of the evolution from a non-virulent HPR0 to a virulent HPR-deleted infectious salmon anaemia virus

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